Three-dimensional quantitative force maps in liquid with 10 piconewton, angstrom and sub-minute resolutions

Abstract

We develop a bimodal force microscopy method to map the three-dimensional force fields and their time-evolution on a variety of solid–water interfaces. The force maps show an oscillatory decaying force perpendicular to the solid surface with a 0.3 nm periodicity. The technique enables the three-dimensional imaging and mapping of the hydration layers and forces on mica and protein GroEL surfaces with 10 piconewton, 2 angstrom and 40 second (whole volume) resolutions. We record the existence and evolution of nanoscale perturbations involving thousands of water molecules of the protein–liquid interface. Those instabilities are not found in stiff and atomically flat interfaces.